Class D airspace is typically associated with which of the following?

Class D airspace is specifically defined as the airspace that surrounds airports with operational control towers. The presence of a control tower indicates that there is a level of air traffic management in place, which is essential for coordinating the arrival and departure of aircraft within that airspace.

Air traffic controllers at these airports provide services to manage the safe and orderly flow of air traffic. This includes issuing clearances, providing instructions for takeoff and landing, and assisting with traffic advisories. The structure of Class D airspace typically extends from the surface to a certain altitude, which varies depending on the airport's specifications.

While some airports with radar facilities and busy airports may have Class D airspace, it is the operational control tower that distinctly marks the airspace as Class D. Airports without control towers fall into other classifications altogether, and although busy airports may have advanced traffic handling processes, what primarily identifies Class D airspace is the presence of the control tower to manage local traffic.